Don't leave the apparatus around after you have finished the day's work.
PART I.—MAGNETISM.
CHAPTER I.
IRON AND STEEL.
1. Introduction. We should know something about iron and steel at the start, because we are to use them in nearly every experiment. The success with some of the experiments will depend largely upon the quality of the iron and steel used.
When we buy a piece of iron from the blacksmith, we get more than iron for our money. Hidden in this iron are other substances (carbon, phosphorus, silicon, etc.), which are called "impurities" by the chemist. If all the impurities were taken out of the iron, however, we should have nothing but a powder left; this the chemist would call "chemically pure iron," but it would be of no value whatever to the blacksmith or mechanic. The impurities in iron and steel are just what are needed to hold the particles of iron together, and to make them valuable. By regulating the amount of carbon, phosphorus, etc., manufacturers can make different grades and qualities of iron or steel.
When carbon is united with the pure iron, we get what is commonly called iron.
2. Kinds of Iron and Steel. Cast iron is the most impure form of iron. Stoves, large kettles, flatirons, etc., are made of cast iron. Wrought iron is the[4] purest form of commercial iron. It usually comes in bars or rods. Blacksmiths hammer these into shapes to use on wagons, machinery, etc. Steel contains more carbon than wrought iron, and less than cast iron.